Communication systems are known to transport large amounts of data between a plurality of end user devices. Such end user devices include telephones, facsimile machines, computers, television sets, cellular phones, personal digital assistants, et cetera. As is also known, such communication systems may be a local area network (LAN) and/or a wide area network (WAN). A local area network is generally understood to be a network that interconnects a plurality of end user devices distributed over a localized area (e.g., up to a radius of 10 kilometers). For example, a local area network may be used to interconnect workstations distributed within offices of a single building or a group of buildings, to interconnect computer based equipment distributed around a factory, hospital, et cetera.
As is further known, local area networks may be wired local area networks or wireless local area networks. Wired local area networks typically have a star topology, ring topology, bus topology, or hub/tree topology. A local area network that utilizes the star topology includes a private automatic branch exchange (PABX) and/or a private digital exchange (PDX). Such devices switch data among the end user devices and/or data terminal equipment (DTE). Such exchange devices allow for voice and/or data to be conveyed between the end user devices and/or the DTE's of the local area network.
A local area network that utilizes a ring topology passes cable access from one DTE and/or end user device to another until all of the DTE's and/or end user devices are interconnected in a loop or ring. The local area network that utilizes a bus topology typically employs one of the Ethernet protocols to convey data within the network. As is known, there are a variety of Ethernet protocols that range from conveying data at rates of 10 megabits per second to multiple gigabits per second. A local area network that utilizes hub technology is essentially a bus or ring topology with the wiring collapsed into a central unit. The central unit includes a set of repeaters that retransmits all of the signals received from the DTE's and/or end user devices to other DTE's and/or end user devices on the same bus or in the same ring.
Wireless local area networks have the end user devices and/or DTE's operably coupled to a server via a wireless connection and a portable access unit. The wireless coupling may be a fixed wire placement, such as for applications by a personal computer, or via portable roaming wireless connections as used by portable devices that vary its location within the local area network. The wireless local area network may utilize a variety of modulation schemes including spread spectrum, quadrature amplitude modulation, time division multiple access, orthogonal frequency division multiplexing, and/or frequency division multiple access.
A wide area network is generally understood to be a network that covers a wide geographic area. Wide area networks include both public data networks and enterprise wide private data networks. The public data network is established and operated by a national network administrator specifically for data transmission. Such public data networks facilitate the internetworking of equipment from different manufacturers. Accordingly, standardization's by the ITU-T have been established for conveying data within public data networks. Currently there are two main types of public data networks; packet switched public data networks and circuit switched public data networks. The public switched telephone network (PSTN) is an example of a circuit switched public data network and the internet is an example of a packet switched public data network. Other examples of wide area networks include integrated service digital networks (ISDN) and broadband multi-service networks.
Regardless of the type of communication system (e.g., LAN or WAN), each communication system employs a data conveyance protocol to ensure the data is accurately conveyed within the system. All such data conveyance protocols (hereinafter referred to as protocols) are based on Layers 1, 2, 3 and/or 4 of the open system interconnection (OSI) 7 layer reference model. As is known, the layers include a physical layer (Layer 1), a data link layer (Layer 2), a network layer (Layer 3), a transport layer (Layer 4), a session layer (Layer 5), a presentation layer (Layer 6), and an application layer (Layer 7).
In general, a protocol is a formal set of rules and conventions that govern how end user devices and/or DTE's exchange information within the communication system. A wide variety of protocols exist, but can be generally categorized into one of four types of protocols; a local area network protocol, a wide area network protocol, network protocol, or routing protocol. The local area network protocols operate at the physical and data link layers and define communication over various local area network media. Wide area network protocols operate at the lower 3 layers of the OSI model and define communication over the various wide area media. Routing protocols are network layer protocols that are responsible for path determination and traffic switching. Network protocols are the various upper layer protocols that exist in a given protocol suite. Examples of such protocols include asynchronous transfer mode (ATM), frame relay, TCP/IP, Ethernet, et cetera.
As is further known, communication systems may be networked together to yield larger communication systems where such networking is typically referred to as internetworking. Internetworking is achieved via internetworking units that allow communication networks using the same or different protocols to be linked together. The internetworking units may be routers, gateways, protocol converters, bridges, and/or switches.
Routers are intelligent devices that connect like and unlike local area networks. They also connect to metropolitan area networks and wide area networks such as X.25, frame relay, and/or ATM based networks. Accordingly, routers operate at the physical layer, the link layer, and/or the network layer of the OSI model to provide addressing and switching. In addition, routers may also operate at Layer 4, the transport layer, in order to ensure end-to-end reliability of data transfers.
A gateway provides an entrance and exit into a communication system. For example, a gateway may be a connection between local area networks, between a local area network and a wide area network, or between wide area networks. Accordingly, a gateway is a node on both networks and provides mapping to all 7 layers of the OSI model. Thus, allowing interfacing between two incompatible systems (e.g., email systems and data file transfer systems) to be interconnected.
A bridge is a data communications device that connects two or more network segments and forwards packets between them. A bridge operates at the physical layer of the OSI reference model and serves as a physical connection between segments, amplifies carrier signals, and buffers data during periods of network congestion. As is also known, bridges are protocol specific (e.g., supports only one of Ethernet, token ring, et cetera).
A switch works at the physical and data link layers of the OSI reference model with emphasis on the data link layer. A switch reads incoming data (e.g., voice or data) to determine a destination address or addresses. Based on each address, a transmission path is setup through a switch matrix between an incoming communication port and an outgoing communication port. In addition, switches include buffering to hold data packets until necessary resources are available to allow packets to be forwarded.
A protocol converter is a communication device that translates a binary data stream from one protocol format into another according to a fixed algorithm. Accordingly, the protocol converter converts data from one protocol to another and may be incorporated in a switch, a bridge, a router and/or a gateway.
As is also known, an internetworking unit has multiple ports (i.e., input ports and output ports) to provide multiple path connections within a network. In operation, an internetworking unit typically receives network data (i.e., packets formatted in accordance with a particular protocol) at multiple input ports, processes the network data received on each input port and outputs the processed data on one or more output ports. As such, for each input port that receives network data, the internetworking unit may output it on one or more output ports after processing it in accordance with the particular functionality of the internetworking unit. To facilitate such a data transfer, the internetworking unit typically stores data words of the incoming packet in an input buffer, subsequently reads the data words out to process them and then stores the process data words in output buffers. Accordingly, the speed of the memory is a significant factor in the speed at which the internetworking unit may process data.
Currently, the speed of memory devices is much less than the desired data rate of internetworking units. For example, a single port dynamic random access memory (DRAM) operates at a rate of approximately 160 megabits per second. To improve the speed of memory, dual port memories, double data rate memories, quad data rate memories, flash memories have been developed. For example, a double data rate memory operates at approximately 320 megabits per second while a quad data rate memory operates at approximately 640 megabits per second. The rate of the memory is established based on the size of the data words being retrieved per read interval. For example, if a data word is 16 bits, and the read rate is 10 megahertz, the resulting memory rate is 160 megabits per second. Accordingly, as the data word size increases, the read rate may be reduced and yet still achieve the particular memory rate. However, as the number of bits in a data word increases, the more pins, PCB traces, and line drivers within integrated circuits are needed. For example, if a desired rate within an internetworking unit is 40 gigabits per second and the system utilizes a 640 megabits per second quad data rate memory, the words sizes would be 125 bits to achieve the 40 gigabits per second rate. As such, multiple quad data rate memories would operate in parallel to achieve the 125 bit data word line which then requires 125 pins on the memory integrated circuits, 125 line drivers within such integrated circuits and 125 traces on the printed circuit board to support such a data rate. Such an implementation would be impractical.
Another issue for internetworking units is that the buffering within the input and output ports may operate at different rates. Thus, when data is conveyed from one port to another, it must operate at the slower of the two rates. Thus, the limitations provided by memory devices are not yielding the desired speeds for internetworking units. This is not a new phenomenon since the desired performance of an internetworking unit has historically led the actual performance of internetworking units and all indications are that this trend will continue.
Therefore, a need exists for a high-speed buffering system that utilizes a minimal number of interconnections to provide data conveyances within a network component, computer system, and/or any other device within a communication system that utilizes buffers as part of a data conveyance scheme.